There has been known a control device for a vehicular power transmitting device including a shifting portion forming part of a power transmitting path between the drive-force source and drive wheels, and an electric motor connected to an input of the shifting portion. For instance, Patent Publication 1 (Japanese Patent Application Publication No. 2006-2913) discloses such a vehicular power transmitting device of a hybrid type. With the control device disclosed in Patent Publication 1, a differential gear device is provided with a switching device with which the differential gear device is properly switched to a differential state or a locked state, thereby preventing the electric motor from reaching a high-speed rotation while enabling regeneration to be achieved with increased efficiency.
Meanwhile, with hybrid type vehicular power transmitting devices including that disclosed in patent Publication 1, the downshift point for the vehicle to run under the decelerating state (during the coast running state) is normally set to a shifting point that prevents occurrences of shifting shock and regeneration torque escape caused by the shifting. In particular, the down shift point for the coast running mode is set such that with a view to avoiding the occurrences of shifting shock and the regeneration torque escape, the downshift point is set to a non-drive region of the vehicle or a region in close proximity to the non-drive region. FIG. 11 is a conceptual view showing the relationship between the vehicle speed and a drive force of the vehicle.
As shown in FIG. 11, negative torque is present in a high vehicle speed region due to regeneration torque. On the contrary, positive drive torque occurs in a low vehicle speed region due to creep torque occurring when controlling, for instance, the electric motor. The vehicle has a non-drive region in close proximity to a boundary point between a regenerating torque region and a creep torque region. The downshift point is set to the non-drive region, thereby suppressing the occurrence of shifting shock during the shifting state and regeneration torque escape.
Since such a downshift point lays in a relatively low vehicle speed region, the output shaft of the shifting portion has a low rotation sped, with accompanying decrease in rotation speed of the electric motor during the regeneration mode. In addition, due to limited torque of the electric motor, the electric motor can hardly obtain adequate regeneration amount (electric power generation amount). Especially, under a circumstance like a case wherein a drop occurs in, for instance, the charge capacity, there is a need for immediately recovering the charge capacity, and under such a situation, a need arises for the electric motor to increase the regeneration amount.